Ecg electrode with partition

ABSTRACT

An improved cup-shaped electrode with holes therethrough to allow both ingress of electrically conductive paste and egress of entrapped air, and with a vertical partition mounted between the holes within the electrode cavity to both guide the flow of paste and air in the cavity and to prevent possible interferences therewith by a surface of the human body with which the electrode is in contact. In certain illustrative embodiments, egress holes number more than one, and vertical partitions may number more than one to improve the efficiency of the electrode.

United States Patent [72] Inventor Christopher C. Day

Newtonville, Mass. [21] Appl. No. 878,740 [22] Filed Nov. 21, 1969 [45] Patented Nov. 30, 1971 [73] Assignee American Optical Corporation Southbridge, Mass.

[54] ECG ELECTRODE WITH PARTITION 6 Claims, 6 Drawing Figs.

[52] 11.8. CI 128/2.06 E, 128/D1G. 4, 128/417 [51] Int. Cl. A6lb 5/04 [50] Field of Search 128/206 E, 2.06 R, 2.1 E, 2.1 R, 404, 417

[56] References Cited UNITED STATES PATENTS 2,590,876 4/1952 Landauer 128/417 3,411,495 11/1968 Casby 128/2.1 E 3,467,863 9/1969 Karsh 128/417 3,474,775 10/1969 Johnson l28/2.l E

Primary Examiner-William E. Kamm Attorneys-William C. Nealon, Noble S. Williams and Robert J. Bird PATENTEDuuv 30 Ian 3, 623 .479

INVENTOR. CHRISTOPHER C. DAY

ATTORNEY BACKGROUND In the rapidly growing field of medical-electronics, there is a continual need for improved ways in which to make reliable and accurate electrical contact with the skin surface of a human being for the purpose of conducting electric current from the body to external measuring and monitoring instrumentation and vice versa. The present state of the art utilizes the procedure whereby a cup-shaped electrode is initially attached to the skin, either by taping over the top of the electrode cup to the skin or by using double-coated adhesive discs between the electrodes rim and the skin, after which an electrically conductive paste is squirted into the electrode cavity through an entrance hole, to assure good electrical contact between the skin and the electrode. Ingression of the paste through the entrance hole into the electrode cavity tends to compress the air entrapped therein, causing egression of that air from an exit hole in the electrode cup.

There are disadvantages associated with this method of making electrical contact. For example, the force from a paste applicator against the rim of the paste entrance hole causes the human flesh to bulge into the electrode cavity, thereby reducing the paste acceptance capacity of the electrode cavity. Accordingly, when the applicator force is removed, the electrode cavity will be only partially filled with paste. f

A second disadvantage is that the aforementioned application of force from the paste applicator can cause the skin to make contact with the paste entrance hole, thereby sealing the hole. Additional paste ingress pressure is required to overcome this seal which is known in the art as a hydrostatic lock; once the seal has been broken this higher paste ingress pressure causes the paste to indiscriminately squirt throughout the electrode cavity and outside thereof onto the skin, resulting in a messy and uncomfortable situation for the person being monitored or measured.

A third disadvantage is that some tend to take the shortest holes. Upon blockage of of the injected paste will path between the entrance and exit the exit hole by paste, entrapped air tially filled with air and partially filled Examples of prior art electrodes are disclosed in U.S. Pat. Nos. 3,295,515 and 3,367,323. U.S. Pat. No. 3,295,5l relates to an electrode assembly for detecting low-level electrical signals from the skin of a living creature disclosing a rigid wall having perforations through which electrolyte flows and makes contact between the skin and the electrode. However, this design still has certain of the disadvantages mentioned above.

U.S. Pat. No. 3,367,323 discloses a cup-shaped electrode held in position by vacuum wherein a web structure prevents the skin from being sucked into the vacuum line. It also has certain of the disadvantages mentioned above.

It is an object of 'the present invention to provide an improved electrode which is designed to make a reliable electrical contact between the surface of a human being and external instrumentation, the contact being superior to that appended by prior art electrodes of which I am aware.

BRIEF DESCRIPTION According to this invention, a partition is vertically mounted within a cupor saucer-shaped electrode between two holes in the electrode body. One hole or aperture, the entrance one, is used to insert electrically conductive paste, after the electrode cup is firmly attached to a human body. The second hole, the exit hole, is used to allow the egress of entrapped air. The partition overcomes the disadvantages mentioned above by preventing flesh from bulging into the electrode cavity and from contacting the cavity wall in the vicinity of either hole. The partition causes the paste to flow around its rounded ends providing a longer flow path between the holes than that which exists without a partition. The partitions rounded ends provides a smooth laminar flow. This flow direction scavenges air from remote areas of the cavity prior to blockage of the exit hole by the paste, insuring substantially a total filling of the electrode cavit DRAWINGS FIG. 1 is a bottom view of an present invention;

FIG. 2 is a sectional view along line 2-2 of FIG. 1;

FIG. 3 is a schematic exemplary view of a prior art electrode;

FIG. 4 is a perspective view of an electrode according to the present invention, schematically indicating a method of connection with external instrumentation; and

FIGS. 5A and 5B are bottom views of alternative embodiments.

Referring to FIG. 1, there is shown a bottom view of an electrode l0, exposing the downwardly opening dish-shape cavity 12 into which electrically conductive paste 22 is injected through entrance hole or aperture 13. The paste is constrained to flow around the ends 28 of vertical partition 15, as schematically indicated by dashed arrows 26, because the partition 15 forms a restricting wall in the paste flow path. The partition extends the distance between skin on which the electrode is placed and the interior surface of the electrode body. This controlled flow also tends to scavenge all entrapped air and guide it out exit hole 14.

As the entrapped air is expurgated, exit hole 14 fills with conductive paste 22. Line 17 represents the edge of the longitudinally vertical plane of symmetry of partition 15 and as shown has a length equal to the distance between ends 28. Line 18 represents a portion of a center line drawn through substantially the centers of holes 13 and 14, and has a length equal to the distance between those centers. Line 17 and line 18 are substantially mutual perpendicular bisectors.

Referring to FIG. 2, there is shown a sectional view of the electrode in which the paste ingress direction 20 is downward and the air egress direction 21 is upward. Electrode-cup rim 23 does not make electrical contact with the skin 16 due to the presence of an insulating washer-type element 29. Electrical contact made with the skin 16 occurs only through conductive paste 38.

The force of the incoming paste and the applicator tends to bulge the skin 16 into the electrode cavity 12 but partition 15 prevents this intrusion by making physical, but not electrical, contact with the skin thereby permitting almost total expurgation of entrapped air, and total filling of the cavity 12 with paste 38. Of course, the partition must therefore be nonconductive.

FIG. 3 is a sectional view of an known to the art prior to the tor l9 creates a downward causing skin 33 to bulge into electrode according to the electrode cup of a type present invention. Paste applicaforce against electrode cup 32 cavity 34, preventing maximum filling of the cavity 34. Upon removal of applicator l9 and the force associated therewith, the cavity will be partially filled with paste 35 and partially filled with entrapped air preventing good electrical contact between the skin 33 and the electrode cup 32. Furthermore, if skin 33 comes in contact with entrance hole 31 creating what is known in the hydraulic art as a hydrostatic lock," then paste ingress pressure must be increased to overcome the hydrostatic lock with the probability that once overcome, the increased ingress pressure will cause the paste to squirt from the confines of the cavity causing a mess. Further still, paste 35 will flow through cavity 34 following a path 37 of least flow resistance (the shortest path between holes 31 and 36). Therefore, paste 36 will not scavenge entrapped air from the extremities of the cavity. This also results in some unexpurgated air and therefore, a poor electrical contact.

FIG. 4 is a perspective view of an electrode according to the present invention showing wire conductor 24 which is arranged to carry electrical signals to and from external instrumentation (not shown).

FIG. 5A is a bottom view of an alternative embodiment wherein many small exit holes 25 are substantially evenly distributed over the electrode cup on the side of partition remote from entrance hole 13. Holes 25 are large enough to allow egress of entrapped air, but small enough to prevent egression paste. The total area of all exit holes is greater than the area or the previously described single exit hole, allowing a more rapid expurgation of air and therefore, a more efficient filling of the cavity 12 with paste.

FIG. 5B is a bottom view of still another embodiment of the present invention wherein the partition 27 is segmented to permit the entrance hole 39 to be placed closer to the rim 23 allowing more efficient expurgation of air lying in the outer periphery of the cavity. This partition segmentation also provides three spaced contact areas with the skin to better restrain the skin from intruding cavity 12 rather than .the single central contact area as found in the embodiment of F IG. 1. Partition segments 27 direct the flow as schematically indicated by dashed arrows 40. Flow distances from entrance hole 39 to exit holes 41 are substantially equal to the flow distances from hole 39 to exit holes 42, providing an even expurgation of entrapped air throughout the cavity. Partition segments 27 have sharp corners as shown to reduce flow re sistance to the entrapped air and conductive paste, and to better guide the flow.

Although several embodiments of the invention have been disclosed herein for purposes of illustration, it will be understood that various changes can be made in the form, details, arrangement and proportions of the holes, partition and electrode cup without departing from the spirit and scope of the invention as defined by the appended claims.

What is claimed is:

l. in an improved electrocardiographic-type electrode. which utilizes electrically conductive paste to assure good electrical contact with a surface of a human body, and including an electrode cup having a rim to accommodate a washer adapted to make physical contact with the body, there being a plurality of holes formed through the cup, the improvement comprising:

electrically nonconductive partition means having substantially vertical ends and being substantially vertically mounted within said cup between said holes for guiding both ingress of said paste and egress of entrapped air and for preventing saidhuman surface from inhibiting paste ingression and air egression.

2. An electrode as set forth in claim 1 wherein:

said holes are two in number and are arranged about said partition means so that a line joining substantially the centers of said holes intersects said partition means substantially equidistant from either of said vertical ends.

3. An electrode as set forth in claim 2 wherein:

a. said partition means terminates in a plane defined by a circular rim.

4. An electrode as set forth in claim 2 wherein:

said partition means is mounted approximately equidistant from either of said holes.

5. An electrode as set forth in claim 1 wherein:

a. said partition means is mounted between a single entrance hole and a plurality of smaller exit holes.

6. An electrodes set forth in claim 1 wherein:

a. said partitions means is comprised of a plurality of segments, said segments together cooperating to provide tortuous flow paths between the ingress and egress holes. 

1. In an improved electrocardiographic-type electrode, which utilizes electrically conductive paste to assure good electrical contact with a surface of a human body, and including an electrode cup having a rim to accommodate a washer adapted to make physical contact with the body, there being a plurality of holes formed through the cup, the improvement comprising: electrically nonconductive partition means having substantially vertical ends and being substantially vertically mounted within said cup between said holes for guiding both ingress of said paste and egress of entrapped air and for preventing said human surface from inhibiting paste ingression and air egression.
 2. An electrode as set forth in claim 1 wherein: said holes are two in number and are arranged about said partition means so that a line joining substantially the centers of said holes intersects said partition means substantially equidistant from eiTher of said vertical ends.
 3. An electrode as set forth in claim 2 wherein: a. said partition means terminates in a plane defined by a circular rim.
 4. An electrode as set forth in claim 2 wherein: said partition means is mounted approximately equidistant from either of said holes.
 5. An electrode as set forth in claim 1 wherein: a. said partition means is mounted between a single entrance hole and a plurality of smaller exit holes.
 6. An electrodes set forth in claim 1 wherein: a. said partitions means is comprised of a plurality of segments, said segments together cooperating to provide tortuous flow paths between the ingress and egress holes. 